The ctypes package

ctypes is an advanced ffi (Foreign Function Interface) package
for Python 2.3 and higher. In Python 2.5 it is already
included.

ctypes allows to call functions in dlls/shared libraries and has
extensive facilities to create, access and manipulate simple and
complicated C data types in Python - in other words: wrap
libraries in pure Python. It is even possible to implement C
callback functions in pure Python.

ctypes works on Windows, Windows CE, Mac OS X, Linux, Solaris,
FreeBSD, OpenBSD. It may also run on other systems, provided that
libffi supports this platform.

The ctypes-users mailing-list is the place to ask questions
about ctypes and related packages; to reduce spam it is now
required to be subscribed before posting. This mailing list is
also available on gmane in several ways.

A codegenerator (old documentation, out of date but you may get
the idea) which will parse C header files and generate ctypes
compatible Python code. There is currently no official release
for the code generator, but you can get it from the ctypeslib SVN
repository.

A pure Python COM package named comtypes, especially useful for
calling and implementing custom COM interfaces without the need to
write C/C++ code. The comtypes SVN repository contains a much
improved version, I will release this asap.